Mine too has that annoying rattle. It sounds like it is inside right rear. However, after trying everthing and listening to you guys, I believe the problem is with the exhaust or shock. I also believe it goes away or is minimized in hot weather. When the weather breaks (midwest cold) I will climb under there and see what I can find.

 

Check out this thread: https://my350z.com/forum/2003-2008-n...g-in-rear.html

I just returned from the dealer (Texas Nissan of Grapevine). Somewhat frustrating....I told them exactly what I wanted to check, brought the print-out of the 'fix' from the above link - and was told they first have to duplicate it before they will fix anything. My response: OK - how do we do that - I have been there multiple times but it still exists.

Another appointment on Wed. After that - yet another dealer.

I wish Nissan would publish a TSB - then maybe we could get the dealer to pay attention...

 

If you do a search you'll find its in most the Z's.For a long time I thought it was the throw out bearing,NEGATIVE.Its a bearing inside the transmission,if not the sync's.I know cause I bought a new throw out bearing and it came right back.Its in Z's from 03 to 07.I think its from driving the Z's transmissions quick and hard(grinding isn't needed to make the transmission rattle)JUST cheaply made.JUST a check in to.I've been a mechanic for 15 years,painting for 5 years. I know what 'm talking about.I have a fully built TT 03 track,03 G35.I had a 07 350z bought wreck that had 3200 miles that rattled.

 

I have a 03 brickyard, n i too have the same exact problem. It seems to be at it's worse during colder days. I believe it's the exhaust since i tightened everything down with my coilovers.

 

Please; a Brick may have a loose nut but a rattle? Never!

 

Check the shields around the rear bumper mounting brackets. I was tapping around mine today and noticed that they have a tendency to rattle a bit.